1. Field of the Invention
The present invention relates to electronic printing and more particularly to the electrodielectric printing apparatus and process as it applies to monochrome and color print engines and toners.
2. Description of the Prior Art
U.S. Pat. Nos. 4,733,256 and 4,777,500, issued to Salmon, describe an electrostatic color printer utilizing a rotating toner drum and an imaging printhead that pulls toner from the drum by coulomb forces. The described embodiments include imaging through orifices in special purpose integrated circuits, as well as imaging by a planar surface with no orifices. Limitations to such printers arise due to the fact that imaging orifices are too easily plugged by dust in the environment. Also, the requirement to charge the toner in order to create coulomb imaging forces results in substantial complexity in the printing machines that have heretofore been described.
There is a need for print engine architectures that are built to optimize the advantages of toners with high relative dielectric constants. High dielectric toners can be imaged by dielectric forces rather than coulomb forces. The dielectric force is created by a charge polarization on the toner particle rather than a net positive or negative charge required for imaging of point charges according to Coulomb's law of electrostatic attraction. The new print engine architectures should avoid the need for imaging orifices and should enable color printer designs that offer simultaneously high resolution, high speed, and sophisticated color capabilities. There is also a need for new dielectric toner materials that can be imaged using relatively weak electrical fields.